Molecular sieves such as zeolites have been used extensively to catalyze a number of chemical reactions in refinery and petrochemical reactions, and catalysis, adsorption, separation, and chromatography. For example, with respect to zeolites, both synthetic and natural zeolites and their use in promoting certain reactions, including conversion of methanol to olefins (MTO reactions) and the selective catalytic reduction (SCR) of nitrogen oxides with a reductant such as ammonia, urea or a hydrocarbon in the presence of oxygen, are well known in the art. Zeolites are crystalline materials having rather uniform pore sizes which, depending upon the type of zeolite and the type and amount of cations included in the zeolite lattice, range from about 3 to 10 Å (0.3 to 1 nm) in diameter.
Zeolites having 8-ring pore openings and double-six ring secondary building units, particularly those having cage-like structures have recently found interest in use as SCR catalysts. A specific type of zeolite having these properties is the zeolite SSZ-52 which has been assigned the framework type SFW by Structure Commission of the International Zeolite Association. SSZ-52 has a three-dimensional 8-ring channel system and is a member of the ABC-6 family of zeolites (stacking sequence AABBAABBCCBBCCAACC), but it has cavities that are significantly larger than any known ABC-6 family member.
U.S. Pat. No. 6,254,849 discloses zeolite SSZ-52 and its synthesis in the presence of an N,N-diethyl-5,8-dimethyl-azonium bicyclo[3.2.2.]nonane cation as a structure directing agent.
The commercial development of SSZ-52 has been hindered by the high cost of the organic structure directing agent required in U.S. Pat. No. 6,254,849 for its synthesis and hence there has been significant interest in finding alternative, less expensive structure directing agents for the synthesis of SSZ-52.
Accordingly, it has now been found that additional relatively simple cations described herein can be effective as structure directing agents in the synthesis of SSZ-52.